Methane production from ethanol co-products in anaerobic SBRs

Abstract

Methane production from condensed distillers' solubles (CDS, or syrup), a co-product of ethanol production, was studied in 2-1 anaerobic sequencing batch reactors (ASBRs) under 10 different operating conditions. Methane production and COD removal were quantified under steady state conditions for a wide range of operating parameters. COD removals of 62-96% were achieved at OLRs ranging from 1.5-22.2 g COD l-1d-1, SRTs from 8-40 d, and F/M ranging from 0.37-1.95g COD g-1 VSS d-1. The methane content of the biogas varied from 57-71% with 0.27 l CH3 produced per g of COD removed. Approximately 54% of the COD fed to the ASBRs, and 83% of the COD removed in the ASBRs was converted to methane. Microbial yield (y) and decay (b) constants were determined to be approximately Y = 0.127g VSS g-1 COD removed and b = 0.031 d-1 respectively. Methane recovery from ethanol co-products can reduce the cost and the fossil fuel consumption of ethanol production. © IWA Publishing 2008.